( 446° ) 
MEMOIR 
ON 
SULPHURIC ETHER. 
BY JOHN DALTON. 
(Read April 16, 1819.) 
> a 
In my essay on the force of steam, read 
before the Society in 1801, and published in 
the 5th volume of the Memoirs, I stated 
some experiments on the force of vapour 
from sulphuric ether, at different tempera- 
tures, as exhibited in a Torricellian vacuum, 
also the force of the same when admitted 
into a limited portion of air. From these 
experiments, as well as from corresponding 
ones made with water, alcohol and other 
fluids, I was led to adopt the important con- 
clusion, that steam acquires the same force 
in air as in a vacuum, and that it ought to be 
considered the same independent fluid in both 
cases. Consequently if p denote the pressure 
of any given volume of air (1), and f denote 
the pressure of steam of a given temperature, 
such steam being admitted to the air, the 
volume of both in due time becomes—_2 r, 
me 
